Anticorrosion agents



Patented Dec. 26, 1944 ANTICORROSION AGENTS Gordon W. Duncan, Scotch Plains, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application July 5, i941,

Serial No. 401,262

Claims. (01. 252-47) This invention relates to improved oil and grease lubricating compositions, which are particularly adapted for the lubrication of metal parts moving upon each other in relative contact at high pressures. It relates particularly to the preparation of high film strength oils for the lubrication of bearings and gears operating under high pressures in the automobile engine system and to the preparation of cutting oil compositions adapted for deep cutting and heavy machining duty.

The present day lubricant adapted for servicing hypoid gears and similar types of machinery parts operating under high pressures are composites in which compounds of chemically reactive character are blended with suitable oil bases. Many of these additive compounds contain reactive sulfur and/or halogen. It would seem that the particularly suitable additives are effective in carrying the heavy loads between the metal surfaces because of a chemical interaction between such compounds and certain elements in the metallic surfaces, and the formation thereby of physically and chemically resistant films, almost of molecular thickness in some cases, which prevent metal to metal contact and scoring or welding of the surfaces.

While the bearing surface films are either stable or satisfactorily changeable in composition under the service conditions involved in the operation of the high pressure bearing equipment, moisture apparently causes the deterioration of the films and the consequent corrosion of the metallic surfaces. Thus, in the presence of moisture, corrosion and substantial staining of ferrous and copper-bearing alloys used in the preparation of bearings, bushings and piston occur, and cutting oil compositions containing the chemically active inorganic elements cause the formation of a black stain on copper alloys. These effects are apparently due to hydrolytic reactions occurring in the interfacial films and the liberation thereby of nascent compounds which corrode the surfaces. Thus, it would seem from the character of the corroded surfaces that the chlorine containing compounds release hydrogen chloride; and th sulfur containing compounds, hydrogen sulfide. It is an object of the present invention to obviate this undesirable corrosion without adversely affecting the desirable properties of the respective compositions.

The discovery and demonstration has now been made that by adding to the high film strength lubricants containing compounds containing one or more active inorganic elements in forms normally corrosive to machinery metals, small amounts of oil soluble soaps or salts derived from organic amines and fatty acids or petroleum naphthenic acids, the undesirable corrosive efiect of these compositions is substantially eliminated. These amine compounds are particularly effective in high strength film compositions such as extreme pressure lubricants, and substantially anhydrous cutting oil compositions containing halogenated and/or sulfurized derivatives of parafiln wax, kerosene and coal tar solvents. The amounts in which these amine compounds are incorporated in the compositions vary between 0.01% and 2% by weight, but in any particular case, the amount employed depends essentially upon the uses to which the composition is adapted. Usually, however, the amount which is added is between 0.1% and 1%.

The amine compounds are also effective when added in amounts between 0.1% and 10% by weight to the concentrated compositions which are often prepared for subsequent blending with relatively larger amounts of lubricating oils or grease bases to prepare the extreme pressure lubricants and the cutting oil compositions. These concentrated compositions are often prepared to simplify later blending treatment and for sales delivery purposes. The addition of the amine soaps to the concentrates is a means of offsetting corrosive tendencies inherent in those compositions during transportation and storage and also of securing the desired concentration of the amine soaps in the fully blended composition. The amine portion of the corrosion preventing compounds usually consists of the mono, di or tri alkyl, cyclo alkyl, or alkylated aromatic, amines and their hydroxy derivatives. Usually the amine portion of a suitable compound has an ionization constant of the order between 10* and 10- but the range is preferably between 10- and 10*. Although it is believed that the degree of ionization or the basicity of the amines is an important factor in the mechanism, it appears that such is not the determining factor becaus such aryl amines as aniline, toluidine, and naphthyl amine falling within this ionization range in combination with the acid components of desirable compounds are only slightly eifective in preventing the corrosion caused by the extreme pressure agents. 011 the other hand, the higher alkylated aryl amines such as those hav ing side chains of 4 to 6 carbon atoms in the molecule, appear to be very suitable, and of these amines the hydroxy derivatives are especially clesirable. It also appears that the acid portion mgs. for the unblended composition.

of the compounds is not a definitely critical factor but it is desirable that the acid contain at least 8 carbon atoms and contribute to the formation with the amine of an oil soluble or easily oil dispersible compound. Oleic, stearic, and palmitic acids are the preferable acids. The preferable type of petroleum naphthenic acids are those derived from petroleum distillates of the kerosene or lubricating oil range or petroleum crude.

Whatever may be the action of th soaps in the composition prepared according to the invention, it appears that this use is distinguishable and different from all prior art uses of the amine compounds in hydrocarbon compositions. It is clear that the use of the amine compounds according to this invention is to minimize the corrosive eifect of compositions containing such chemically active constituents as sulfur and chlorine containing compounds on metallic surfaces, and as such this use is distinguishable from the efiect of the soaps in hydrocarbon containing compositions such as forexerting pour depressant, oil-thickening, and emulsifying effects. It

is reasonable to believe upon the basis of observations made during the service in the lubrication of hypoid gears, that the compounds exert'prohibitive effects upon oxidation reactions and that they are truly corrosion preventives. Under service conditions in hypoid gears it appears that some decomposition of. the amine compound occurs. It appears in thecase of fatty acid derivatives that the nascent fatty acids produced by the decomposition contribute to the oiliness of the surface film, and that the nascent arnines have some stabilizing action upon the film itself as the result of inhibiting-tendencies therein to oxidation and in removing water from the sphere of harmful effect by reason of a-measure of emulsifl cation. The preparation of cutting oil composi- 40 amine compounds in essentially,anhydrouscomtions according to the invention, employs the positions, the so-called straight cutting oil compositions. These blended compositions are used for heavy duty and deep cut machining work and to a less extent for heat transfer purposes. These compositions contain as their constituents asaaoia v 'Example 2 The above test was repeated with 1% of oleic acid soap of an alkylated tertiary phenolic amine known commercially as Hyamine B, in the ex treme pressure lubricant and no evidence of corrosion was observed.

Example 3 The test in Example 1 was repeated with the lubricant containing 1% of the oleic acid soap of an alkyl hydroxy benzyl amin prepared by condensing a paratetramethyl butyl phenol with paraformaldehyde in benzene solution in the presence of hydrogen chloride, 'then reacting the condensation product with liquid ammonia or an amine compound. No evidence of corrosion was observed and the testspeoim'ens were in excellent condition.

The physical and chemical bases of the activities of the amine compounds of this invention are incorporated in the compositions. This effect would appear to be connected with particular features of chemical combination, such as structure and balance between the acidity and basicity of the acid and amine portions respectively of the compounds. Also, there is reason to believe that thedesirable amine compounds of this in-' vention have some effect ;in preventing the hya mineral oil and in lesser amount a halogenated and/or sulfurized organic compound. This type cutting oil has to be distinguished from the cutting oils prepared from soluble mineral oils and" water which contain; amine soaps as emulsifying agents and are used mainly as cooling media in light metal machining work.

A better understanding oi the invention is conveyed in the followin illustrations:

Example 1 I n An extreme pressure lubricant was prepared containing 8% sulfurized sperm oil (12% sulfur) pieces in a. bottle through which moist air was passed for 24 hours. When 1% by weight ofdicyclohexyl amine naphthenate was blended in the composition and the test repeated, no corrosion was evident upon the metal test pieces. Furtherdrolysis of the load-bearing films formed between the metal surfaces-and also in reacting with nascent corrosive compounds formed near the interfaca. These properties of the amine compounds would appear to be connected with the surface active characteristics of the compounds and the basicity of the amine portions thereof. These desirable characteristics of the compounds .of the invention are noticeable particularly in extreme pressure lubricants containing corrosive chlorine and/or sulfur compounds.

Although the present invention has been described in connection with details of specific examples and some discussion has been given to theoretical consideration, it is not intended that the invention be limited thereby. In the following claims it isintended to cover all the novelty inherent in the invention.

What is claimed is: I 1. A substantially anhydrous lubricating composition of high load-bearing characteristics comprising a mineral oil admixed with a compound containing halogen .and sulfur in a form normally corrosive to metals, said compound being adapted to increase the load-bearing capacity of the oil, and a dicyclohexylamine' salt'of an organic acid selected from, the group consisting of high molecular weight fatty acids and petro- 'leum naphthenic acids, said salt being present in more, the load carrying capacity of the'lubricant in the above test was 2.7 mgs. compared to 24 amounts sufficient to inhibit corrosion of'metals by said composition.

2. An extreme pressure lubricant comprising a major proportion of a mineral lubricating oil, a

. normally corrosive halide adapted to increase the extreme pressure lubricating characteristics of saidoihand a compound formed by the reaction of dicyclohe'xylamine with an organic acid selected iromthegroupconsistingoi'high molecular weight fatty acids and petroleum naphthcnic acids, said compound being present in amounts sufllcient to inhibit corrosion by said lubricant.

3. An extreme m lubricant comprising a major proportion of a mineral lubricating oil, a normally corrosive compound containing at least one element selected from the group consisting of halogen and sulfur, said compound being adapted to increase the extreme pressure lubrieating characteristics of said oil, and a compound formed by the reaction of dicyclohewlamine with 5 inhibit corrosion by said lubricant.

4. A composition according to claim 1 in which said salt is a derivative of a fatty acid containing at least eight carbon atoms.

5. An extreme pressure lubricant according to 10 claim 3 in which said organic acid is a fatty acid containing at least eight carbon atoms.

GORDON W. DUNCAN. 

